Retailers that are struggling are ones that rely on selling a
uniform, branded look — think the logo-heavy Abercrombie &
Fitch circa the early 2000s. (The company has been making
numerous changes to its assortments to appeal to the
way millennials think and shop, though it hasn't wholly paid off just yet.)

But it also means that retailers need to be able to adapt
rapidly— especially as they prefer for the generation after
millennials, Gen Z, which Marcie Merriman, Gen Z expert and
Executive Director of growth strategy and retail innovation
at Ernst &
Young, called "millennials on steroids."

Millennials have some brand loyalty; Gen Z does not.

"So it really is a level of tolerance and what they're
willing to accept, anda degree of brand loyalty,"
Merriman said in an interview with Business Insider this past
winter. "So millennials still have a little bit of loyalty to
different brands or places that they've shopped."